Yesterday, she made the familiar trip, leaving her home in London at 4am to travel to the former mother-and-baby home.

In 1952 she gave birth to her son Anthony who she was forced to give up for adoption. Her son went on to become Michael Hess, chief counsel to the Bush and Reagan administrations.

This time, though, hundreds of others joined her for the first annual commemoration service for those mothers and babies who died in the home.

They watched as Ms Lee put flowers on her son’s grave to add to the bounty of flowers already there. Somebody had also put a candle on the grave with a picture of Michael Hess and a quotation from William Butler Yeats’s poem A Drinking Song.

Ms Lee has renewed the whole debate about the forced adoption of Irish children which went on for decades. The book and the successful film Philomena has helped to uncover so many dark secrets from Ireland’s past which keep coming, most recently with the revelation last week that a mass grave found in Tuam may have been the burial ground for nearly 800 children from a mother-and-baby home.

The commemoration service took place in a beautiful secluded children’s cemetery in the grounds of the abbey. The many graves were ringed with flowers and flags of the US, Britain and various US states, including Alaska, symbolising the international dimension of these adoptions.

Yesterday’s commemoration had two purposes, according to one of the organisers, Susan Lohan of the Adoption Rights Alliance. The first was to remember those who died while residing with the Sisters of the Sacred Heart of Jesus and Mary; the second was to press for an investigation into forced adoptions. “A great deal of sorrow started here,” she said.

This event will be held every year “until we get the fulsome apology from the State”.

Ms Lee never got to meet her son after he was taken from her aged 2½ and adopted in the US. He died in 1995. There are many similar stories without a happy ending.

One woman called Anne, who asked that her surname not be revealed, was separated from her son Andrew at Sean Ross Abbey in 1965.

She was told simply that he had gone and it was never explained to her whether “gone” meant dead or adopted.

“It is hard for me to see this crowd here today,” she told the crowd yesterday, her voice breaking. “When we were here, we were all alone and nobody came to see us. Nobody apparently cared. Our dark history has to become less dark.”

Bridget Cummins and her two siblings visited on behalf of their mother Josephine who gave birth to a girl in the abbey in 1954. The three siblings met their sister, who lives in Chicago, in 2002, but, unfortunately, their mother was dead by then.

As with Ms Lee’s case, mother and daughter had been searching for each other but the nuns, it is alleged, never passed the information on.

“Philomena’s here and her son’s gone, we’re here and our mother is gone. Our mother was told the same lies,” she said.